What's the Outlook For Winter?

Ken Ring says this winter should be milder, with both snow and warm rain.

Perigee is the day in the month when the earth-orbiting moon passes closest to earth. Within the week of perigee come higher tides and extreme weather. Perigees this winter are on 6 May, 4 June, 2 July, and 24 August.

The perigee cycle is independent of the full moon-new moon cycle. A colder winter is when winter months combine perigee with the new moon phase.

May of this year through to August will see full moon accompany perigees rather than the new moon. It means that the cold of winter during full moon nights will not be as cold as usual for the time of year.

Winter nights and temperature minimums should be milder, at least until September.

By October and November new moon perigees again rule, bringing a cooler late spring. The last half of October should bring widespread precipitation, which means unwanted late snow for the south and the chances of floods in the north; because perigeal spring new moons create large cool low-latitude anticyclones and their strong moist easterlies sweep rain in large amounts over eastern coasts. It may come too late for any ski field to capitalise on.

Overall for winter relatively warm winter nights will make for milder days. The really good long snow seasons will not return before 2016. This season should be similar to some of the early 2000 years, the early part of the 1990s and some of the later 1970s, which were years of similarity of moon declinations.

So, says Ken, if you are a skier plan carefully. The snow will come, then rain should wash it away, only to be followed again by snow. The South Island may be more easily able to run snow machines for longer periods than the North Island. Some ski-fields may be lucky to have 10 days of southerlies all winter, whereas the more southerly fields can expect between 20-30. Winds are important when working out which snowfields will get the best snow.

Whakapapa can get good snow from just about all winds, including northerly, while Turoa gets best snow from wind coming from the south. Treble Cone needs westerly or north-westerly winds and gets virtually nothing from southerlies. Mt Hutt needs southerlies or south-easterlies, also easterlies if they are cold enough. Coronet Peak needs southerlies or south-westerlies, although not many southerlies carry precipitation. If Treble Cone is getting snow, Coronet probably isn't. Ohau needs southerlies and westerlies. From south-easterlies the Southern lakes just seem to get cloud. Cadrona gets snow from south-westerlies and southerlies, but little or none from the west or north-west. This season should see southeasterlies in good measure, which, being subtropical, can carry warmth. In turn this creates precipitation, rain in the north and snow in the south.

This winter, for the Chateau, expect more westerly systems than easterly systems in May, June and July; and more winds from the east during August. For Ohakune, there should be more westerly systems than easterly systems in May and July, but with rather calm conditions in June and August. For Mt Hutt, there may be westerly systems as well as easterly systems in May, then systems more westerly in June and July, followed by many easterlies in August. For Queenstown, expect cold southerlies and westerlies in May, easterlies in June, and southerlies and southwesterlies in July. August in Queenstown brings easterlies in the first half switching to southwesterlies in the second half. Finally for Wanaka, expect westerlies and northwesterlies in May, westerlies in June and July, and westerlies and northwesterlies through August.